An analytical model to evaluate the fatigue crack effects on the hybrid photovoltaic-thermoelectric device

Abstract

A hybrid photovoltaic and thermoelectric device can effectively increase utilization of solar systems. In this article, an analytical model to evaluate the fatigue cracking and its effect on electric power of a hybrid photovoltaic-thermoelectric device is proposed. Both the analytical and simplified expressions of crack length and electric power versus the cyclic number are presented. It is found that combining thermoelectric module with photovoltaic cell of a small temperature coefficient 0.001 K-1 can improve the total electric power by 7.8%. Inclusion of thermoelectric module with photovoltaic cell of a large temperature coefficient 0.004 K-1 reduces the total electric power by 3.3%. The electric power of the hybrid device is inversely proportional to the cyclic number. For photovoltaic cells with small temperature coefficient, the total electric power decreases with crack propagation. The total electric power increases with crack propagation for photovoltaic cells of large temperature coefficient. The thickness ratio of photovoltaic cell to the insulating layer is optimized to eliminate the interlaminar shear stress thus greatly enhance lifetime. Lifetime of the hybrid devices can be availably improved by appropriately increasing thickness of the insulating layer. The optimized length of thermoelectric module for obtaining the maximum electric power output is given.